need to know what everyone thinks

[carpsak09]

i am doing a frame up on a 76 bronco. I am trying to figure out the driveline that i want to go with and i am playing around with this combination. this will mostly be driven on weekends around town with some light wheelin thrown in every once in a while. I have read alot of the previous posts and have not seen anything on this combo. If anyone has it let me know what you think about it.

351W crate engine
nv3550 trans
dana 20 J
35" tires
3.50 gears

 

[Scoop]

The 3.50's are too high for 35's. I would suggest 4.11 or 4.30 for mostly street driven.

 

[scsm76]

With the OD of the 3550 I would go with 4:56

 

[SteveL]

you might even think of 4:88 gears having the OD. I'm running 4:56 with standard 4th gear(same as 3rd on the 3spd). twin stick the j-shift dana 20.

 

[carpsak09]

I have already purchased the twin stick setup from Wild Horses but thanks for the suggestion. As for regearing to 4.56 or 4.88 which would be the best choice ratio wise. Other than the new gears do I need to upgrade anything else ie. carrier, axles. I am not putting in a locker and already have new chrome molly 30 spline axles which i will use if i can. Man all this talk is making me want to get out in the garage, I got some old shock mounts to grind off.

 

[bronconate68]

I would go with the 4:56s. They will make for a better freeway rig. If you were planning on running more trails I would go with the 4:88s. They will only be more useful for trail runs or launching off the line. I guess there is one more benefit, larger tires.

I currently run 4:88s with 37" tire. At 60 mph I'm running 3000rpms. I have no over drive. With an over drive, say .78 I would be running 2500 to 2700 rpms, that's a guess, which would be more appealing for me. But if I wanted to run 70mph +, for any distance, I would need the 4:56s. I still run up to 80 mph, because I like to, but it is higher on the rpms then I like and I don't like to hold it there for any distance.

You do not need to change the carrier or axles to change the gears.

 

[Mudbone]

You will have to change the carrier in the front D-44 to go to 4.11, 4.30, 4.56, etc, but you can use the same carrier in the rear Ford 9".

 

[silverbullet]

Personally I would go with an auto. 4r70w seems to be a nice upgrade and can be had at the right U-Pull-It. Just my .02. Oh yeah go with 4.56's.

 

[TonyPDX]

I run the 4R70W, 4.88's and 35" tires. The OD is .70 on the 4R70W, so I would recomend 4.56 gears because of the .78 OD on the NV3550 for a primarily street driven rig.

Tony

 

[wildbill]

I would recommend 4:56 or lower with 35" tires or you will have a dead dog in town good luck. Bill %) ;D

 

[carpsak09]

I would put an automatic in but after seeing my buddy drive his bronco with a manual trans i cant resist. It just looks so much more fun.

 

[Amac70]

I would go 4.88 or lower maybe even 5.13. with my zf and 4.56 and 35s i have to be going 60+ to get into 5 th gear and hold Im only turning about 2200rpm at 65. That might sound good but my little 302 (my 302 was brand new also) just didn't have the umph to hold that unless on flat highway. Hopefully my new 351 will.

 

[OX1]

Hmmmm, assuming a std 3 speed first gear ratio of 2.99 vs the new first gear of 4.0 and the 35 vs a 30 inch tire, overall gear ratio in 1rst gear will still be 14% better than stock. 2nd gear will be 26% better than stock. 3rd gear will be 20% better than stock. 4th gear will act as a slight .85 ratio overdrive (again, compared to stock). 5th will be a killer overdrive @ .66.

Seems to me, that with the a substantial power increase of the 351, and the fact you will still have 14-26% better gearing in gears 1-3, 4th will be a nice slight OD for around town, and 5th a killer OD for great highway milage. I don't see the need to regear. The AOD has a.67 OD ratio and it makes for some killer MPG. (dads 93 crown vic pulls an easy 24 MPG @ 80-85 mph, granted with 2.73 rear, but still, it's 4000+ lbs and a V-8).

Now if your going to do moderate or above crawling, then by all means go 4.56 or better. My 3 cents............

 

[Amac70]

There are not many motors that would be able to pull an overdrive with 35 inch tires and overdrive. Go to a calculator and figure it out 3.5 gears 35's and a .80 overdrive your pulling 1750 rpms at 65. Not to many motors will hold that other then going down hill or perfectly flat (maybe)

 

[cj54]

With a 5 speed, 3.50 gears and 35'' tires you wouldn't be able to use 4th gear let alone overdrive, unless you were going downhill.

 

[OX1]

There are not many motors that would be able to pull an overdrive with 35 inch tires and overdrive. Go to a calculator and figure it out 3.5 gears 35's and a .80 overdrive your pulling 1750 rpms at 65. Not to many motors will hold that other then going down hill or perfectly flat (maybe)

Hmm, buddy of mine ran his stock 3.55 geared F350 with an anemic stock 351W, ZF and 38's down the highway pretty well in 5th for several years. Sure he had to downshift on decent hills, but we are talking a low HP stock 351W, another 2500 lbs heavier and larger dia tires, higher lift with more air resistance.

Since we've gotten to calcs, what do most 35's actually measure, usually less than 35 and on the vehicle they are maybe 16 inches from the hub to the ground. Technically, wouldn't that be more like a 32 (if were going to plug in numbers), hence more liek 1911 RPM @ 65 with stock gears.

With 4.88's, first gear becomes real short with 25 MPH being 5000RPM. Constantly short shifting first gets old fast (ask anyone who's driven a 435 or T-18 and stock tired, 3.5 geared equipped fullsize!!!). Even with 4.56's @ 75 MPH in 5th, your pratically screaming @ 2900 RPM.

With a 5 speed, 3.50 gears and 35'' tires you wouldn't be able to use 4th gear let alone overdrive, unless you were going downhill.

Maybe with a heep 4cyl.......... I ran my 78 bronc with stock 351M, 435 trans, stock 3.5 gears and 44 boggers (thats 800 lbs worth of tires) for almost 2 years until I got money for gears, and a motor. It was legal to drive on the street back then and it road 55-60 down the highway........ Sure I had to downshift for anything but flat ground, but to say it wouldn't do it is laughable (and thats a very extreme example). Toledo ain't exactly the mountains. ;D

I'd expect a 250-280 HP W in a rig thats 1500-2000 lbs less wieght, lower to the ground, less frontal area, and substantially less tire weight to be able to pull much higher than 65 MPH. Again, just my opinion from years of creating underfunded beaters with big tires and stock gears.

 

[Dave]

Just for reference, 302 - ZF - 3.55 - 31" tires is undergeared on the road. Bigger tires is not an option until I install 4:11 gears. Then I'll put 33"s on it.

 

[halfcab76]

i am doing a frame up on a 76 bronco. I am trying to figure out the driveline that i want to go with and i am playing around with this combination. this will mostly be driven on weekends around town with some light wheelin thrown in every once in a while. I have read alot of the previous posts and have not seen anything on this combo. If anyone has it let me know what you think about it.

351W crate engine
nv3550 trans
dana 20 J
35" tires
3.50 gears

For what little off roading your doing I would forget the 35" and go with 33" and keep the 3.50 gears or go 4.11. Of course I see I'm the only one that thinks that way. I have use them all but 38" in my 21+ year of driving an EB, I have 35" again.

 

[OX1]

Just for reference, 302 - ZF - 3.55 - 31" tires is undergeared on the road. Bigger tires is not an option until I install 4:11 gears. Then I'll put 33"s on it.

Wow, you guys are picky................. Isn't that drivetrain real close to a stock late 80's F350 with 32ish stock tires?? (265/75/16), assuming a 351W and an extra 2000 lbs would be about equal to an EB with a 302??

 

[TonyPDX]

OX1 I think your buddy’s rig must have been a real exceptional rig!

I now run a Supercharged 5.8L, 4R70W, 4.88 gears and 35” tires. I used to run a normally aspirated 351W, 4.56 gears, 35” tires but the engine was frequently lugging and the transmission was shifting out of OD a lot! With the 4.88’s the OD is very useable, it drives great around town and I got almost 14mph on my last road trip even though I am still tuning the EEC.(4R70W Over Drive = 0.70:1 65 MPH @ ~2200 RPM)

The NV3550 Over Drive = 0.78:1, so w/35” tires:
With 3.54 gears, 65 MPH @ 1722 RPM
With 4.56 gears, 65 MPH @ 2219 RPM
With 4.88 gears, 65 MPH @ 2375 RPM

Additionally the first gear/final drive ratio would be hard on clutches with 3.54 gears and 35” tires. 25MPH would only be 4099 RPM w/4.88 vs. 2973 w/3.45 gears, but who wants to go 25MPH in first gear?!

I sure didn’t like driving mine with the 302, 3spd, 3.54 gears and 33” tires! Anyone can drive a rig with a poor gear ratio but why would you do it by choice?
I stick by my recommendation of 4.56 gears for this application.

Gear calculations from: http://www.grimmjeeper.com/gears.html